1. Center for Plasma Edge Simulation
Validation on inward propagation of turbulence property and edge rotation source rate at L-H transition
C.S. Chang and S. Ku
Courant Institute of Mathematical Sciences, New York University
At C-mod Ideas Forum , 2009
Center for Plasma Edge Simulation

2. Whole-device ITG simulation in DIII-D with C-Mod like collisionality
Turbulence propagates inward from pedestal and dominates the transport property in the core
Central turbulence is generated by heating, but contained under self-generated ExB shearing.
Can we validate the inward propagation of a different turbulence property from pedestal at H-mode transition?
- Time scale ~ ms

3. The compressed turbulence in the density pedestal starts almost simultaneously. However, it appears that there is an inward ballistic propagation of turbulence peak starting from the pedestal.
Separatrix
f119
Density pedestal top
Inward propagation of
ITG turbulence front

4. Pedestal makes difference to the core temperature gradient
Simulation from pedestal top to magnetic axis, R/LT self-organizes to ~6.5
Simulation including pedestal, R/LT self-organizes to ~9
4.5keV, 5MW
R/LT ~ 9
R/LT ~ 6.5

5. Spontaneous toroidal flow generation in the pedestal and in the central heating region (adiabatic electrons)
Can we measure the rotation generation rate in the pedestal?

6. Density profile in poloidal flux

7. Almost initial Ti profile in poloidal flux

9. XGC1: Ion thermal conductivity i profile
I increases from ~1 m2 at r/a =0.5 to 3m2/s at T-pedestal top, then decreasing in the pedestal.
Effective ion thermal conductivity (m2/s)
Minor radius (normalized poloidal flux)
Heating-driven i
(artificial)
Increasing toward edge
Decreasing in pedestal